In recent years, image forming apparatuses have been disclosed which were configured to display schedule images to show the schedules of jobs to be executed by said apparatuses (see Unexamined Japanese Patent Application Publication Number 2004-348,713). According to said apparatus, information for the types of sheet is displayed on the vertical axis, while information for working times and the number of sheets to be used are displayed on the horizontal axis, so that the schedule of the jobs to be executed are displayed.
Normally, various image forming apparatuses make it possible to receive a tray specifying job to manually specify a sheet-feeding tray as a source tray, as well as to receive an automatic selection job, to automatically determine a sheet-feeding tray as the source tray. Concerning the tray specifying job, the operator specifies a sheet-feeding tray which the operator wants to use. For example, the operator specifies the sheet-feeding tray, in such a case for example, that the operator wants to print personal names on diploma sheets, carrying a blank portion for the personal name, accommodated on the sheet-feeding tray, or in case that the operator wants to print images on the back and front surfaces of the sheets, accommodated on a sheet-feeding tray whose back and front surfaces adjustment value have been adequately controlled.
However, in the conventional image forming apparatuses, when the tray specifying job is executed, the productivity rate may deteriorate. That is, if a specified sheet-feeding tray is empty, or if the contents of sheets, accommodated on the specified tray, are not equal to the contents of sheet ordered by the job, the job cannot be executed, and the image forming apparatus displays that the job cannot be executed. The operator cannot understand what to do on the various trays to overcome such cases, which cases take long times to recover the apparatus to be executable, which result in deterioration of the productivity rate.
The present invention has been achieved to solve the above problems, and an object of the present invention is to supply an image forming apparatus, which is able to increase the productivity rate in the above cases.